As electrophotographic photoconductors for use in electrophotographic image-forming apparatuses, inorganic photoconductors having a photosensitive layer composed of inorganic materials, such as selenium, and amorphous silicon, and organic photoconductors having the photosensitive layer mainly composed of organic materials, such as a binder resin, a charge-generating material, and a charge-transporting material, are known.
Among these photoconductors, organic photoconductors have been widely used because, compared with inorganic photoconductors, they are more easily produced, have wider selectivity of materials for the photosensitive layer, and provide for higher design freedom.
Phthalocyanine pigments are widely used as the charge-generating material for such organic photoconductors. In particular, a titanyl phthalocyanine crystal having a Y-type crystal structure has been proposed as the charge-generating material which can improve electrical characteristics of the photoconductors.
On the other hand, the titanyl phthalocyanine having specific physical properties has been proposed as the charge-generating material included in the photosensitive layer of a single-layer electrophotographic photoconductor, the titanyl phthalocyanine having excellent storage stability with respect to organic solvents.
Furthermore, in order to suppress the generation of exposure memory due to a change in surface potential after exposing resulting from an increase in the number of trap sites produced by repeated image formation and to prevent degradation in image characteristics, there has been proposed an electrophotographic photoconductor including at least a charge-generation layer and a charge-transport layer disposed in that order on an electrically conductive support, in which the charge-transport layer includes the charge-generating material having absorption at the wavelength of image exposure light.